This invention, which is a result of a contract with the United States Department of Energy (Contract No. DE-AC05-840R21400), relates generally to methods and systems for measuring beam parameters of a laser, and more specifically to methods and systems for continuously monitoring the output beam parameters of a pulsed or continuous wave laser without interrupting or intercepting any portion of the laser beam.
There are numerous applications in which it is desirable to continuously monitor and/or control beam parameters of a laser, especially high power pulsed or continuous wave (CW) lasers, without interrupting the laser beam or redirecting a portion of the beam. In all known prior art techniques for monitoring laser beam parameters, the beam is either blocked completely or redirected into a calorimeter or thermopile or a portion of the beam is reflected into a lower energy detecting and measuring device. The problem with either of these methods is that the beam must be at least partially interrupted or perturbed in order to make beam parameter measurements.
In systems which block the beams of high power lasers completely the devices are subject to permanent damage and, further, personnel are at risk through exposure to the laser beam itself during power output measuring operations. In addition, these devices obviously cannot respond to rapidly changing laser power levels which are necessary in applications where continuous monitoring of the beam is necessary.
Although attempts have been made to improve the beam monitoring techniques of especially high power lasers by monitoring a portion of the beam rather than blocking the beam entirely to make power measurements, these devices all require some form of reflection or redirection device which introduces beam perturbations that alter the beam power and thus the accuracy and reliability of the measurement. Therefore, there is a need for a system and method to continuously monitor the beam parameters of a laser which does not intercept any portion of the beam.